Brush holder



Sept. 2, 1930. o. c. SCHROEDER BRUSH HOLDER- Filed Feb. 9, 1928 Inven'tow: ()scen C. Schroeder; Wm

His Attorney Patented Sept. 2, 1930 UNITED STATES PATENT OFFICE OSCAR C. SCHROEDEB, OF CHICAGO, ILLINOIS, ASSIGNOR TO GENERAL ELECTRIC COM- PANY, A CORPORATION OF NEW YORK BRUSH HOLDER Application filed February 9, 1928. Serial No. 253,191.

My invention relates to brush holders for electrical machines and has for its object the provision of a brush holder which will pre-- vent chattering of the brushes. I accomplish this by the use of a simplified brush holder including a brush guide in which the brush spring extends along the brush and is supported between the brush and the brush guide so that the force of the spring urges the brush against the current collecting device and against the trailing side of the brush guide with respect to the direction of rotation of the current collecting device of the machine in which it is used. Urging the brush against the trailing side of the brush guide in this manner substantially prevents chattering of the brush because vertical movement which would cause chattering is resisted by the friction of the brush in the brush guide; and lateral movement which would cause chattering is resisted by the frictional force between the brush and the current collecting device and the action of the brush spring which produces a lateral force acting in the same direction. In addition to preventing chattering of the brushes this construction has the further advantage of simplifying the brush holder and enabling one to use a tension spring therein which will maintain the desired brush pressure on the current collecting device without adjustment as the brush is worn away.

Further objects and advantages of my improved brush holder will become apparent as the following description proceeds, and the features of novelty which characterize the same will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawing, Fig. 1 is a longitudinal section of my improved brush holder, Fig. 2 is a transverse section on the line 2-2 of Fig. 1, and Fig. 3 is a diagrammatic view indicating the external forces acting on the brush.

Referring to the drawing, a current collecting device 10 of an electrical machine rotates in the direction indicated by the arrow 11 and a brush 12 is supported in contact therewith by my improved brush holder.

ing device.

This brush holder comprises a tubular, metal brush guide 13 having a longitudinal opening 13 extending therethrough slidably fitting the brush 12. In order to minimize chattering of the brush a suitable spring is arranged along the side of the brush and supported in such manner as to exert a force which urges the brush toward the current collecting device and toward the trailing side of the brush guide with respect to the direction of rotation of the machine. In the construction illustrated by way of example, it is preferred to do this by forming a recess which in this instance is shown as a groove 3" in the wall of the leading side of the brush guide extending longitudinally of the brush and arranging a tension spring 14 in the recess" which is connected to the brush guide by a cross pin 14 and to the brush by a connector 1.5. The connector extends into an opening 12 in the top of the brush and to one side of the same into the groove 13" where it engages a loop 15 formed on the end of the spring.

In this construction it will be noted that the direction of the external forces acting on the brush are, as shown in. Fig. 3, the force F of the spring 14-, the resisting force R exerted by the current collecting device 10 on the brush 12. and the forces r and r exerted by the brush guide on the n-ush 152. The brush is maintained in equilibrium under the action of the spring 14. as the forces F and R produce a moment tending to turn the brush about an intermediate transverse axis which is resisted by an equal and opposite moment produced by the forces r and 7" which repre sent the forces exerted by the brush holder 13 on the brush. It will thus be seen that the spring 14 increases the pressure and friction between the brush and the trailing side of the brush guide so that vertical movement of the brush tending to cause chattering is resisted but not enough to prevent the brush sliding in the brush guide under the action of the spring i l and following any irregularities in the surface of the current collect- Moreovcr, during operation of the machine, the frictional force between the current collecting device and the brush acts to set the brush guide so 111g utterg the side the use selected to exert sure on the brush from the tween the b g 141 111011 er permit 1111 he inserted in the holder 1s worn away.

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GQYO. 

